When writing literary criticism, or when writing any work that seeks to interpret and understand a work of literature, it is helpful to have an understanding of literary theory, also known as critical theory. Theory and criticism go together, in fact. The idea of criticism is not necessarily linked to a critical reading of a text in a negative sense; rather, criticism is a way of reading a text closely and understanding its structure, origins, meanings and implications within wider contexts. According to this scholarly article on the subject, this theoretical discipline is undergoing changes to accommodate cultural change:
"Literary theory," sometimes designated "critical theory," or "theory," and now undergoing a transformation into "cultural theory" within the discipline of literary studies, can be understood as the set of concepts and intellectual assumptions on which rests the work of explaining or interpreting literary texts.
In using critical theory to examine and interpret a text (for example, novel), it is important to understand the basis of the particular theory you're working with. It is possible to use a general critical approach based in literary structure, but for many texts a more specific approach is entirely appropriate. Some critical theories are based upon more specific sets of assumptions, in order to provide a more focused reading of the text. These examples include Marxist theory (which examines texts based upon economic and class inequality for example), feminist critical theory (also known as gender theory, which is intended to closely examine the text's expression of gender roles, sexism, and cultural attitudes about gender, among other topics), or post-colonialism (a theory that includes awareness of the impact of colonialism, or the settlements imposed upon indigenous peoples by white Europeans, on a text's cultural implications).